The recent arrest of six individuals living in the United States, accused of attempting to aid and support the Islamic State in Iraq and Syria (ISIS), underscores the continuing threat posed by radicalized individuals operating within the respective borders of the United States and her Western allies.

The group, hailing from Missouri, Illinois and New York, respectively, are accused of sending military equipment to an ISIS operative who himself left St. Louis in 2013 to fight alongside ISIS in Syria.

In addition to the recent group accused of supporting ISIS, there have been numerous other arrests related to Americans, or those legally residing in the United States, making direct overtures to assist myriad Islamist groups throughout the world.

This includes 19-year-old Shannon Maureen Conley, recently sentenced to four years in federal prison for conspiring to join ISIS in Syria. Conley was arrested last year at Denver International Airport while attempting to travel to Turkey and become a nurse embedded within ISIS.

Another 19-year-old, Mohammed Hamzah Khan, was arrested at Chicago’s O’Hare International Airport in October as he attempted to travel to the Middle East and join with ISIS. Khan, of Bolingbrook, Ill., is also accused of attempting to provide material support to ISIS.

While the idea of disaffected youth or mentally disturbed individuals gravitating toward the lure of fighting overseas or providing material support for terror is disconcerting enough an even more troubling, though latent, threat remains: Namely, individuals, or small groups of individuals, focusing their aggression and anger toward homeland targets.

Recent terror events such as the lone-wolf attack on the Canadian Parliament in October, the Charlie Hebdo massacre in Paris, and subsequent murders at a kosher deli in Porte de Vincennes are grisly reminders of how only a handful of determined terrorists can bring a community, city or even nation to its knees.

Even more troubling is the thought of a small group of individuals, with even just a rudimentary understanding of tactics and weapons manipulation, engaging in coordinated and simultaneous attacks against soft targets within a community.

Duplicating an attack similar to the one that befell the offices of Charlie Hebdo, and then multiplying it by two or three, would induce mass chaos and severely strain the capabilities of even the most sophisticated and prepared domestic law enforcement agencies.

A senior leader of al-Qaeda's affiliate in Yemen claimed responsibility for the attacks on the offices of satirical magazine Charlie Hebdo that killed 12 people in Paris on Jan. 7. (Photo: Polaris/Newscom)

A senior leader of al-Qaeda’s affiliate in Yemen claimed responsibility for the attacks on the offices of satirical magazine Charlie Hebdo that killed 12 people in Paris on Jan. 7. (Photo: Polaris/Newscom)

The thought of such a scenario whereby, for example, three groups consisting of two or three heavily armed individuals each, coordinate simultaneous attacks against diverse soft targets portends unimaginable consequences.

And such and attack is certainly not without precedent.

The 2008 Lashkar-e-Taiba attacks in Mumbai serve as a cautionary tale as to the physical devastation such an attack can impart within a city as well as the lingering psychological repercussions impacting an entire nation or region.

In over three days of terror, 10 Pakistani men attacked myriad facilities in Mumbai, killing 164 people and injuring hundreds more. Nine of the attackers were eventually killed and a lone, surviving terrorist taken into custody. The surviving terrorist would be executed in 2012.

If one considers such an attack to be beyond the scope of the “conventional” homegrown radical consider this: A recent report estimated over 20,000 foreign fighters had traveled to Syria and Iraq to support ISIS in its regional reign of terror. This estimate includes approximately 3,400 foreign fighters traveling to the region from Western origins.

Many of these individuals will attempt to return to their Western homes armed with the knowledge, experience, and grit that can only come through the experience of fighting on the front lines.

And some will undoubtedly slip through the counterterrorism and intelligence web designed to prevent their return home. These individuals, in particular, pose a significant threat to the security of the West.

Preventing an attack such as this, or mitigating the damage thereof, first requires acknowledging the breadth and scope of the threat being faced. Once acknowledged, a preparatory mindset must be adopted by all stakeholders including, but not limited to, state and local law enforcement officials and the federal, state, and local governments overseeing their preparations.

Denial and equivocation only increase the likelihood that such tragedies materialize. By contrast, awareness followed by steadfast vigilance will serve as the greatest safeguard against the bloody machinations of ISIS and its frenzied adherents.